Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Seismotectonics of the central Denali Fault, Alaska, and the 2002 Denali Fault earthquake sequence

Natalia A. Ratchkovski, Stefan Wiemer and Roger A. Hansen
Seismotectonics of the central Denali Fault, Alaska, and the 2002 Denali Fault earthquake sequence (in The 2002 Denali Fault earthquake sequence, Charlotte Rowe (editor), Douglas Christensen (editor) and Gary Carver (editor))
Bulletin of the Seismological Society of America (December 2004) 94 (6, Part B): 156-174

Abstract

In this article we analyze the spatial and temporal variations in the seismicity and stress state within the central Denali fault system, Alaska, before and during the 2002 Denali fault earthquake sequence. Seismicity for 30 years prior to the 2002 earthquake sequence along the Denali fault was very light, with an average of four events with magnitude M (sub L) > or =3 per year. We observe a significant increase in the seismicity rate prior to the M (sub w) 7.9 event of 3 November 2002 within its epicentral region, starting about 8 months before its occurrence. The majority of the aftershocks of the M (sub w) 7.9 event are located within the upper 11 km of the crust and form several persistent clusters with a few aseismic patches along the ruptured fault. The most active aftershock source is associated with the epicentral region of the earthquake. The overall b-value of the aftershock sequence is 0.96 with the highest b-values within the epicentral region. We estimate that it will take 14 years for the seismicity rate to drop back to the background level. The stress regime across the region varies in space and time. The inferred stress regime prior to the 2002 sequence is predominately strike slip. Along the central part of the rupture zone, the orientations of the least- and intermediate-stress axes are reversed after the 2002 earthquake sequence. The maximum compressive stresses along the Denali fault rotate clockwise by up to 35 degrees ; the greatest rotations occur in the area of the rupture step-over from the Denali to the Totschunda fault. The inferred stress regime after the 2002 sequence reflects an interchanging thrusting and strike-slip faulting along the ruptured fault. The thrust faulting is concentrated in the epicentral region of the M (sub w) 7.9 event and along the rupture segments showing the largest surface offsets.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 94
Serial Issue: 6, Part B
Title: Seismotectonics of the central Denali Fault, Alaska, and the 2002 Denali Fault earthquake sequence
Title: The 2002 Denali Fault earthquake sequence
Author(s): Ratchkovski, Natalia A.Wiemer, StefanHansen, Roger A.
Author(s): Rowe, Charlotteeditor
Author(s): Christensen, Douglaseditor
Author(s): Carver, Garyeditor
Affiliation: University of Alaska at Fairbanks, Alaska Earthquake Information Center, Fairbanks, AK, United States
Affiliation: Los Alamos National Laboratory, Los Alamos, NM, United States
Pages: 156-174
Published: 200412
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 74
Accession Number: 2005-040988
Categories: SeismologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch maps
N62°00'00" - N64°00'00", W148°00'00" - W142°00'00"
Secondary Affiliation: University of Alaska, USA, United StatesCarver Geologic, Kodiak, AK, USA, United StatesETH-Hoenggerberg, Swiss Seismological Service, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200525
Close Modal

or Create an Account

Close Modal
Close Modal